She seems so much larger than life in the gossip columns: a freshly divorced Hollywood celebrity, starting a new life in New York City, her comings and goings (six-year-old daughter Suri in tow) obsessively chronicled by the paparazzi. On the Broadway marquee her name stands out in huge letters; the crowds waiting outside the stage door after every performance are just as big. Katie Holmes on Broadway — it’s news.

Onstage, however, she looks unexpectedly small and unimposing: a pretty, rail-thin actress, dressed in fashionably faded jeans and sneakers, trying to impersonate a mousy, thirtysomething Midwestern homebody in Theresa Rebeck’s new comedy Dead Accounts. Four years ago, I thought she made a perfectly acceptable Broadway debut in Arthur Miller’s All My Sons. But here the former Mrs. Tom Cruise is overwhelmed by her co-star and lost in a mediocre play.

She’s hardly the only Hollywood star finding the going tough on Broadway this season. Jessica Chastain works hard as the lovelorn daughter of a rich doctor in turn-of-the-century New York in The Heiress, but succeeds only in reminding theatergoers how much better Cherry Jones was in the same role a decade ago. Debra Winger is forced to recite some of David Mamet’s most archly stylized dialogue, playing a jailer engaged in a philosophical debate with her prisoner (Patti LuPone), a former radical activist, in The Anarchist. Scarlett Johansson at least has a more promising role in the upcoming Cat on a Hot Tin Roof — if you can really stand another revival of Cat on a Hot Tin Roof.

In Dead Accounts Holmes plays Lorna, the good sister who has stayed in Cincinnati to live with her churchgoing mother (Jayne Houdyshell) and ailing father (offstage suffering from kidney stones). Her brother Jack (Norbert Leo Butz) has arrived unexpectedly from New York City, bringing cartons of his favorite Cincinnati ice cream and some secrets that will be dutifully revealed in the course of two fairly short acts.

Rebeck, a prolific but overrated playwright (Omnium Gatherum, Mauritius, last season’s Seminar — as well as TV’s behind-the-scenes Broadway drama Smash) is good at coming up with plot hooks and writes superficially plausible dialogue, but typically falls back on clichés and contrivances to make her fairly trite thematic points. Dead Accounts sets up a familiar conflict: between grounded Midwestern values and those of the big bad city, New York. Jack is a hyped-up, fast-talking, foot-jiggling Manhattanite, who gets all woozy about coming home, while flaunting his Armani suit and dropping names of hot New York restaurants. He’s got a rich society wife, who is divorcing him and who shows up midway through the play to show off her snobbishness; she complains on the phone about the tacky linoleum floors and Corelle dishes— “so deliberately without taste” — just as her mother-in-law wanders into the room and overhears every word. Awk-ward!

Little that happens in the play is very convincing. When he comes home, Jack doesn’t even say hello to his ailing father (whose kidney stones soon develop into pneumonia — go figure), but the reasons for their rift aren’t even hinted at. Jack’s old high school friend Phil hangs around the house pining for Lorna; though they’ve lived in the same town for more than 30 years, he hasn’t asked her out since high school. Worst of all, the big secret around which the play revolves — Jack has supposedly embezzled money from the “dead accounts” of the bank he works for — is such a facile MacGuffin that I thought it would turn out to be a red herring, or a figment of his imagination. Alas, it wasn’t.

Norbert Leo Butz, a Tony-winning Broadway pro, chews up the scenery as the hyperkinetic Jack, while Holmes is reduced mainly to exasperated reactions — to his thievery, to the news of his divorce, to the eight boxes of pizza he brings home when she only asked for one. Her slender frame and whiny, Valley Girl voice doesn’t really convey the angst of a Midwestern woman worried about the mounting years and pounds, and she doesn’t fill the stage, even in her big speeches — like a wistful account of planting a tree as a child on Arbor Day.